Fresh produce should be stored and transported at a temperature as close as possible to that at which the particular produce will not ripen too quickly, or have interior freezing, etc. Depending upon the produce to be stored, adjustments in the operation of an air conditioning system must be made to give the desired temperature for a particular product. To be as error proof as possible, the manual adjustment required to be made by a storage employee or a truck driver should be as simple as possible. When a load has been cooled to near a desired set point of above 20.degree.F. and only a small amount of cooling is needed to obtain or maintain the desired temperature, it has been found that repeatedly cycling a compressor on and off is hard on the equipment and it does not provide a very close air temperature control.
It would therefore be desirable to design an air conditioning system that requires merely the adjustment of a set point to obtain and maintain an accurate desired temperature for storing a particular product. The temperature should be maintained as close as possible without repeated cycling of the compressor and regardless of extreme changes of temperature outside the storage compartment.